[RFC/PATCH 3/3] receive-pack: allow a maximum input size to be specified

[Christian Couder <christian.couder@gmail.com>]

From: Jeff King <peff@peff.net>

Receive-pack feeds its input to either index-pack or
unpack-objects, which will happily accept as many bytes as
a sender is willing to provide. Let's allow an arbitrary
cutoff point where we will stop writing bytes to disk.

What has already been written to disk can be cleaned
outside of receive-pack.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 builtin/receive-pack.c | 12 ++++++++++++
 t/t5546-push-limits.sh | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+)
 create mode 100755 t/t5546-push-limits.sh

diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 92e1213..7627f7f 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -46,6 +46,7 @@ static int transfer_unpack_limit = -1;
 static int advertise_atomic_push = 1;
 static int advertise_push_options;
 static int unpack_limit = 100;
+static off_t max_input_size;
 static int report_status;
 static int use_sideband;
 static int use_atomic;
@@ -212,6 +213,11 @@ static int receive_pack_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
+	if (strcmp(var, "receive.maxsize") == 0) {
+		max_input_size = git_config_ulong(var, value);
+		return 0;
+	}
+
 	return git_default_config(var, value, cb);
 }
 
@@ -1650,6 +1656,9 @@ static const char *unpack(int err_fd, struct shallow_info *si)
 		if (fsck_objects)
 			argv_array_pushf(&child.args, "--strict%s",
 				fsck_msg_types.buf);
+		if (max_input_size)
+			argv_array_pushf(&child.args, "--max-input-size=%lu",
+				max_input_size);
 		child.no_stdout = 1;
 		child.err = err_fd;
 		child.git_cmd = 1;
@@ -1678,6 +1687,9 @@ static const char *unpack(int err_fd, struct shallow_info *si)
 				fsck_msg_types.buf);
 		if (!reject_thin)
 			argv_array_push(&child.args, "--fix-thin");
+		if (max_input_size)
+			argv_array_pushf(&child.args, "--max-input-size=%lu",
+				max_input_size);
 		child.out = -1;
 		child.err = err_fd;
 		child.git_cmd = 1;
diff --git a/t/t5546-push-limits.sh b/t/t5546-push-limits.sh
new file mode 100755
index 0000000..d3a4d1a
--- /dev/null
+++ b/t/t5546-push-limits.sh
@@ -0,0 +1,47 @@
+#!/bin/sh
+
+test_description='check input limits for pushing'
+. ./test-lib.sh
+
+test_expect_success 'create known-size commit' '
+	test-genrandom foo 1024 >file &&
+	git add file &&
+	test_commit one-k
+'
+
+test_expect_success 'create remote repository' '
+	git init --bare dest &&
+	git --git-dir=dest config receive.unpacklimit 1
+'
+
+test_expect_success 'receive.maxsize rejects push' '
+	git --git-dir=dest config receive.maxsize 512 &&
+	test_must_fail git push dest HEAD
+'
+
+test_expect_success 'bumping limit allows push' '
+	git --git-dir=dest config receive.maxsize 4k &&
+	git push dest HEAD
+'
+
+test_expect_success 'create another known-size commit' '
+	test-genrandom bar 2048 >file2 &&
+	git add file2 &&
+	test_commit two-k
+'
+
+test_expect_success 'change unpacklimit' '
+	git --git-dir=dest config receive.unpacklimit 10
+'
+
+test_expect_success 'receive.maxsize rejects push' '
+	git --git-dir=dest config receive.maxsize 512 &&
+	test_must_fail git push dest HEAD
+'
+
+test_expect_success 'bumping limit allows push' '
+	git --git-dir=dest config receive.maxsize 4k &&
+	git push dest HEAD
+'
+
+test_done
-- 
2.10.0.rc0.4.g229e32c.dirty